Effect of related parameters on exposure age and erosion rate obtained via rock surface luminescence dating

Abstract

BackgroundRock surface luminescence dating has developed rapidly in the past decade. It has been widely used to obtain exposure ages and erosion rates of various rocks in archaeology, geology, and geography, such as stone artifacts, glacier bedrock, gravel, and bedrock fault surfaces. However, these is little study on the effect of parameters related to this method, such as attenuation coefficient μ, decay rate of the trapped charge at the rock surface σφ0¯, environmental dose rate D˙, and characteristic saturation dose D0 on exposure age and erosion rate results.PurposeThis study aims to quantitatively investigate the impact of relevant parameters on exposure age and erosion rate, and examine the limits of exposure age and erosion rate obtained by the method under different parameters.MethodsFirst, parameters that might have an impact on age and erosion rate results were determined through theoretical analyses. Then, the relationship among the parameters, depth of half saturation and exposure age (erosion rate) were studied using numerical simulations. The impact of each relevant parameter on exposure age and erosion rate was observed for varied parameter values. Finally, the dating limit was determined from the inflection point in the simulated profiles.ResultsThe smaller μ value is, the greater the rate of change in the depth of half saturation would be when increasing the same exposure time. However, the rate of change in the depth of half saturation remains constant for different σφ0¯ values when the same erosion rate is increased.ConclusionsAmong the parameters, σφ0¯ and, more remarkably, μ significantly affect the dating result. In general, D˙ and D0 have little effect on the exposure age and erosion rate; therefore, the differences in D˙ between the surface and interior of rocks may be ignored. The growth rate of depth of half saturation of granite gneiss is significantly higher than that of sandstone for the same exposure time increment. Therefore, light-colored rocks such as granite should be prioritized for collection during field work. The ranges of dating and obtaining erosion rate using this method are 10-3~102 ka and 10-2~103 mm∙ka-1, respectively.

Keywords

• rock surface
• luminescence dating
• erosion rate
• light attenuation parameter
• numerical simulation